1. Field of the Invention
The present invention relates to processes for molding wire coils. More particularly, though not exclusively, the present invention relates to an apparatus and method for molding wire coils while accurately maintaining the pitch of the coils.
2. Problems in the Art
In some areas of the telecommunications field such as wireless communications, transceivers include an antenna which may telescope into a housing of the transceiver. A typical retractable antenna will include a small coil in the bottom of the housing which is used when the antenna is in the retracted position. These lower coils are critical to the performance of the transceiver. Small variations in the dimensions and pitch of the coil affect the performance of the transceiver. Naturally, any manufacturing process that does not maintain the required tolerances will result in lower coils which have an unsatisfactory and inconsistent performance. There is currently no prior art method of producing lower coils which accurately and consistently control the pitch of the coil.
A typical lower coil for a wireless telephone and the like is comprised of a wire coil encapsulated in a plastic molding. Prior art attempts at creating lower coils by an injection molding process are unsatisfactory since during the injection molding process, the pitches of the coil vary from the springs expanding and/or contracting resulting in coils tuned to various frequencies rather than to a consistent desired frequency. One example of a use of such a coil is with GSM devices. GSM is an international platform used with cellular phones around the world. The GSM frequency range is 800-900 MHz.
In addition, in any industry it is desired to automate labor intensive practices. In a typical lower coil molding process, an operator may frequently need to intervene with the process. The requirement of an operator for the molding machines naturally requires more labor cost.
It can therefore be seen that a process of using injection molding to create encapsulated lower coils is desired which keeps the pitch of the coils to a desired pitch.
Typical prior art lower coil molds have been used having one and two cavity molds with a parting line along the side with the wire coil laid down horizontally. When the plastic is injected around the coil, the coils move causing a variation in the pitch and therefore a variation in the tuned frequency. These prior art methods typically held the wire coil around a smooth surface where they make a few points of contact on the outside of the coil. The injection pressure from the plastic and the velocity of the plastic allows the plastic to get in between and move the pitch of the coil around which causes electrical performance problems.
Therefore, a need can be seen for an apparatus and process for efficiently and accurately manufacturing molded lower coils which maintains high tolerances for the coil with minimal requirements for manual intervention.